The Effect of Penetrator® and Penetrator Plus® on Pesticide Deposition, Evaporation, and Foliage Residue in Cotton

Marion E. Farris


 
ABSTRACT

Droplet density and coverage are increased by the addition of PENETRATOR® or PENETRATOR PLUS® to aerially applied sprays. A spray volume of 18.7 L/ha (2 gal/A) without the adjuvant produced 7.3 droplets/cm2 at the 30 cm (1 ft.) level in a cotton canopy compared with 18.5 droplets cm2, when 0.6 L/ha (8 oz/A) of PENETRATOR PLUS® was added to the solution. Percent coverage was also increased from 0.53% to 120% by adding PENETRATOR PLUS®. Both increases were significant. When PENETRATOR PLUS® was added to a spray volume of 9.3 L/ha (1 gal/A), droplet density increased from 154% to 309%, and when added to a spray volume of 28.1 L/ha (3 gal/A), droplet density increased from 160% to 210%. When compared to a ULV vegetable oil at 2. 4 L/ha (1 qt/A), total spray volume, PENETRATOR PLUS® at 0.6 L/ha significantly increased (PSO.01) droplet density and percent coverage over the ULV spray solution. when summer temperatures are high and cotton insects are present at all levels of the cotton plant, it is imperative to have sufficient droplet density and coverage for cotton insect control. These results indicate coverage is increased when PENETRATOR® or PENETRATOR PLUS® is used with water as compared to the ULV oil technique or water alone.

PENETRATOR® at 0.6 L/ha in a spray volume of 18.7 L/ha and applied at a height of 6.1 m (20 ft.) slowed the rate of dissipation and increased droplet density when compared to water alone. Percent area covered was similarly affected. Tinder similar evaporative conditions, 33 IC (91 IF) and 60% relative humidity, spray solutions with PENETRATOR® released from 9 m had greater deposition and higher droplet density and coverage at all levels than sprays without PENETRATOR®.

Residue analysis conducted as part of this study indicates an affect on the amount and half-life of the pesticides delivered to the target. As an example, Cyhalothrin at 33.6 g/ha (0.03 lb/A) at a pH of 6.9 in water alone had a residue of 0.5 ppm at 24 and 72 hours. When 0.6 L/ha @8 oz/A) PENETRATOR PLUS® was added to the spray mixture, residues were increased to 2.5 ppm at the 24 hour measurement and 0.8 ppm at the 72 hour period. With a pH of 6.9 alkaline hydrolysis was not a factor. Similar differences were seen in other pesticides. When organophosphates were tested in water with a pH of 8.0 and 8.5, alkaline hydrolysis was probably a factor in the amount of residue found on the foliage at both sampling periods. The buffering capacity of PENETRATOR PLUS® appears to have an affect on the pH and alkaline hydrolysis.



Reprinted from 1991 Proceedings Beltwide Cotton Conferences pp. 768 - 771
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998